Die set with stripper plate

ABSTRACT

Disposed between the upper punch holder and lower die holder of a die set is a stripper plate that is movable vertically relative to both holders. The plate is suspended from the punch holder and between them there are springs that resist movement of the plate and punch holder toward each other when the plate is pressed against the work being punched. Guide posts rigidly mounted in the punch holder extend down through guide passages in the stripper plate and into vertical passages in the die holder. A bearing sleeve is mounted on each guide post for vertical movement thereon and extends through the adjoining stripper plate passage and down along the post. A bushing encircling this sleeve, which it engages, fits in a bearing sleeve mounted in an underlying passage in the die holder. The upper ends of the bushings are rigidly connected to the stripper plate. The bushings hold the stripper plate against tilting relative to the punch and die holders.

United States Patent [1 1 Vecchi July 3, 1973 DIE SET WITH STRIPPERPLATE Primary ExaminerAndrew R. .Iuh'asz Assistant Examiner-Horace M.Culver 75] inventor: John C. Vecchi Natrona Her hts, Pa. l g Attorney-Brown, Murray, Flick & Peckham [73] Assignee: Oberg Manufacturing Co.,lnc.,

FYCBPOYL [57 ABSTRACT Filed! June 14, 1971 Disposed between the upperpunch holder and lower die holder of a die set is a stripper plate thatis movable vertically relative to both holders. The plate is suspendedfrom the punch holder and between them there are springs that resistmovement of the plate and punch holder toward each other when the plateis pressed against the work being punched. Guide posts rigidly mountedin the punch holder extend down through guide passages in the stripperplate and into vertical passages in the die holder. A bearing sleeve ismounted on each guide post for vertical movement thereon and extendsthrough the adjoining stripper plate passage and down along the post. Abushing encircling this sleeve, which it engages, fits in a bearingsleeve mounted in an underlying passage in the die holder. The upperends of the bushings are rigidly connected to the stripper plate. Thebushings hold the stripper plate against tilting relative to the punchand die holders.

4 Claims, 4 Drawing Figures [52] [1.8. CI 83/140, 83/637, 83/698 [51]Int. Cl B26d 7/18, B26f 1/02 [58] Field of Search 83/637, 140, 698; I308/237 A, 237 R, 4 C, 6 B

[56] References Cited UNITED STATES PATENTS 2,364,835 12/1944 Whistleret a1. 83/140 2,422,774 6/1947 Conner 308/4 C 2,997,907 8/1961Constantino 83/637 2,428,698 10/1947 Deichmil1er.. 83/140 3,140,6307/1964 Wolf 83/140 3,357,755 12/1967 Danly 83/637 X 2,906,563 9/1959Conner 83/637 X 3,417,643 12/1968 Bennett 83/637 X 3,631,765 1/1972Neumeister 308/6 B DIE SET WITH STRIPPER PLATE Die sets are known inwhich a spring-loaded stripper plate is disposed between an upper punchholder and a lower die holder for holding the work down on the dieholder while the punch or punches are withdrawn from it. Guide postsmounted in the punch holder extend down through the stripper plate andinto vertical passages in the die holder for guiding the punch holder asit reciprocates. In addition to stripping, a second purpose of thestripper plate is to help guide the punches that slide up and down inthe plate. Usually, to guide the stripper on the guide posts it isprovided with short bushings, only slightly longer than the thickness ofthe plate, that slide on the guide posts. Nevertheless, if somethingapplies uneven pressure to the stripper in operation, the stripper willcock or tilt and thereby deflect the punches and cause them to strikethe die face instead of entering the openings in the die.

It is among the objects of this invention to provide a die set, in whicha spring-loaded stripper plate is guided in such a manner that it cannottilt and deflect the punches.

The preferred. embodiment of the invention is illustrated in theaccompanying drawings, in which FIG. 1 is a plan view of the die set;

FIG. 2 is an enlarged end view, with the die set open;

FIG. 3 is an enlarged vertical section taken on the line III-III of FIG.1, but with the die set closed; and

FIG. 4 is a further enlarged horizontal section taken on the line I-VIVof FIG. 2.

Referring to the drawings, a lower die holder 1 is rigidly mounted on asuitable base and supports a die 2 that may be provided with a pluralityof vertical openings 3 through it that are aligned with similar openings4 down through the holder for disposal of the punchings. The die maysupport a pair of laterally spaced guide rails 5, between which thework, such as a metal strip 6, is fed.

Spaced above the die holder is a punch holder 8 that is supported byconventional means (not shown) by which the holder can be moved towardand away from the die holder. The punch holder carries punches 9 thatextend down below it in alignment with the die openings 3. To guide thepunch holder in its vertical movements, the upper ends of guide posts 10are rigidly mounted in it, with the posts extending down into verti calpassages 11 in the die holder.

Between the two holders there is a floating stripper plate 13 secured tothe lower ends of studs 14 that are slidably mounted in verticalpassages 15 through the punch holder. When the die set is open, i.e.,the punch holder is at the top of its stroke as shown in FIG. I, thestripper plate may be roughly midway between the punch holder and thedie holder. The central part of the plate is provided with passages 16,in which the punches are slidably disposed. The stripper plate also isprovided with vertical guide passages 17, through which the guide postsextend. When the die set is closed, which means that the punch holder isat the bot- I tom of its stroke, as shown in FIG. 2, the stripper plateis moved down into contact with the top of the work 6, which stopsfurther downward movement of the plate, but the punch holder continuesdown to cause the punches to punch the work. When the punch holderstarts to move up again, the stripper plate remains pressed tightlyagainst the work for a short time because coil springs 18 encirclingstuds 14 between the plate and the punch holder were compressed when thedie set was closed and therefore must expand again before the studs canstart to lift the stripper plate. The action of the die set as describedthus far is conventional.

It is a feature of this invention that the stripper plate 13 will guidethe punches without any danger of the plate tilting and therebydeflecting the punches so that they may not enter the die openings.Accordingly, a bushing 20 encircles each guide post 10. The bushings fittightly in the stripper plate passages 17, but are spaced from the guideposts. The bushings also extend down the posts and into the die holderpassages 11 at all times. To attach the bushings to the stripper platethey may project above it and have enlarged upper ends seated on theplate and provided with circumferential grooves 21, in which lugs 22 areseated. These lugs are attached to the top of the stripper plate byscrews 23. The space between each guide post and the surrounding bushing20 is filled by a bearing sleeve that can move vertically relative toboth of them. Such a sleeve preferably is one formed from a cylindricalcage 24 provided with a plurality of radial openings, in each of whichthere is a small ball 25 that presses tightly against both the post andthe bushing. This gives the rigidity required and keeps the bearingsleeves in place. It will be seen that as the guide posts move up anddown in the bushings, the bearing sleeves will likewise move verticallybut only half as far as the posts.

The portions of bushings 20 within the die holder passages 11 are spacedinwardly from the walls of those passages, which may be formed by hardliners 27 rigidly mounted in the passages. The space between theseliners and the guide post bushings are likewise filled by bearingsleeves 28 of the same construction as those previously described. Thislower set of bearing sleeves likewise moves up and down with the guidepost bushings, but only half the distance that they move.

With the guide post bushings 20 not only rigidly mounted in the stripperplate but also rigidly mounted in the die holder, except that they canmove vertically in the holder, the bushings will guide the stripperplate at all times and prevent it from cocking or tilting, which coulddamage the punches. Nothing can get out of alignment, so the die set cansafely be operated at very high speed.

According to the provisions of the patent statutes, I have explained theprinciple of my invention and have illustrated and described what I nowconsider to represent its best embodiment. However, I desire to have itunderstood that, within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically illustrated anddescribed.

I claim:

1. A die set comprising an upper punch holder and lower die holder, atleast one punch extending downwardly from the punch holder, a normallyelevated stripper plate disposed between and spaced from said holdersand movable vertically relative thereto, the plate having apunch-receiving opening therethrough, means suspending the plate fromthe punch holder, springs between the punch holder and plate urging theplate away from the punch holder, the plate being provided with verticalguide passages therethrough, guide posts rigidly mounted in the punchholder and extending down through said plate passages, the die holderhaving vertical passages therein containing said posts, a lower bearingsleeve mounted in each die holder pasdie set is open and are disposedsubstantially entirely within the die holder while the die set isclosed.

3. A die set according to claim 1, in which said bushings project abovethe stripper plate, and said connecting means are mounted on top of saidplate and are secured to the upwardly projecting bushings.

4. A die set according to claim 3, in which the bushings above thestripper plate are provided with circumferential grooves, and saidconnecting means are lugs projecting into said grooves.

* it I i

1. A die set comprising an upper punch holDer and lower die holder, atleast one punch extending downwardly from the punch holder, a normallyelevated stripper plate disposed between and spaced from said holdersand movable vertically relative thereto, the plate having apunch-receiving opening therethrough, means suspending the plate fromthe punch holder, springs between the punch holder and plate urging theplate away from the punch holder, the plate being provided with verticalguide passages therethrough, guide posts rigidly mounted in the punchholder and extending down through said plate passages, the die holderhaving vertical passages therein containing said posts, a lower bearingsleeve mounted in each die holder passage for vertical movement therein,a bearing sleeve mounted on each guide post for vertical movementthereon and extending through the adjoining stripper plate passage anddown along the post, a bushing fitting tightly in each plate passage andlower bearing sleeve and encircling the post-mounted bearing sleevetherein in engagement with it, and means rigidly connecting the upperends of the bushings to the stripper plate, whereby said bushings holdthe stripper plate against tilting relative to said holders.
 2. A dieset according to claim 1, in which said lower bearing sleeves extendabove the die holder while the die set is open and are disposedsubstantially entirely within the die holder while the die set isclosed.
 3. A die set according to claim 1, in which said bushingsproject above the stripper plate, and said connecting means are mountedon top of said plate and are secured to the upwardly projectingbushings.
 4. A die set according to claim 3, in which the bushings abovethe stripper plate are provided with circumferential grooves, and saidconnecting means are lugs projecting into said grooves.